This invention relates to devices for the treatment of heart disease and particularly to endoarterial prosthesis, which are commonly called stents.
Several interventional treatment modalities are presently used for heart disease including balloon and laser angioplasty, atherectomy, and by-pass surgery. In typical balloon angioplasty procedures, a guiding catheter having a preformed distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient in a conventional Seldinger technique and advanced within the cardiovascular system until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire is positioned within an inner lumen of a dilatation catheter and then both are advanced through the guiding catheter to the distal end thereof. The guidewire is first advanced out of the distal end of the guiding catheter into the patient's coronary vasculature until the distal end of the guidewire crosses a lesion to be dilated, then the dilatation catheter having an inflatable balloon on the distal portion thereof is advanced into the patient's coronary anatomy over the previously introduced guidewire until the balloon of the dilatation catheter is properly positioned across the lesion.
Once in position across the lesion, the balloon which is made of relatively inelastic materials, is inflated to a predetermined size with radiopaque liquid at relatively high pressure (e.g., greater than 4 atmospheres) to compress the arteriosclerotic plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilatation catheter can be removed therefrom.
Further details of dilatation catheters, guidewires, and devices associated therewith for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson, et al.); U.S. Pat. No. 4,554,929 (Samson, et al.); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); and U.S. Pat. No. 4,748,982 (Horzewski, et al.) which are hereby incorporated herein in their entirety by reference thereto.
A major problem which can occur during balloon angioplasty procedures is the formation of intimal flaps which can collapse and occlude the artery when the balloon is deflated at the end of the angioplasty procedure. Another major problem characteristic of balloon angioplasty procedures is the large number of patients who are subject to restenosis in the treated artery. In the case of restenosis, the treated artery may again be subjected to balloon angioplasty or to other treatments such as by-pass surgery, if additional balloon angioplasty procedures are not warranted. However, in the event of a partial or total occlusion of a coronary artery by the collapse of a dissected arterial lining after the balloon is deflated, the patient is put in an extremely dangerous situation requiring immediate medical attention, particularly in the coronary arteries.
A major focus of recent development work in the treatment of heart disease has been directed to endoprosthetic devices called stents. Stents are generally cylindrically shaped intravascular devices which are placed within a damaged artery to hold it open. The device can be used to prevent restenosis and to maintain the patency of blood vessel immediately after intravascular treatments. In some circumstances, they can also be used as the primary treatment device where they are expanded to dilate a stenosis and then left in place.
But the rapid and effective delivery of a stent to the desire location within the patient's vasculature has been found to be difficult, particularly in those situations in which an intimal flap has occluded an artery. Attempts to advance a stent into regions of coronary arteries occluded by dissected arterial linings have not been very successful.
The two basic methods and systems have been developed for delivering stents to desired locations within body lumens. One method and system involves compressing or otherwise reducing the diameter of an expandable stent, disposing the compressed stent within a lumen provided in the distal end of a tubular catheter, advancing the catheter through the patient's vasculature until the distal end of the catheter is immediately adjacent to the desired vascular location and then pushing the stent out the distal end of the catheter into the desired location. Once out of the catheter, the compressed stent expands or is expanded to thereby hold open the artery or other body lumen into which it is placed.
Another method and system involves disposing a compressed or otherwise small diameter stent about an expandable member such as a balloon on the distal end of a catheter, advancing the catheter through the patient's vascular system until the stent is in the desired location within a blood vessel and then expanding the expandable member on the catheter to expand the stent within the blood vessel. The expanded expandable member is then contracted and the catheter withdrawn, leaving the expanded stent within the blood vessel, holding open the passageway thereof.
The following references illustrate various types of stents and stent delivery systems. The list is meant to be exemplary, not exhaustive on the subject.
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What has been needed and heretofore unavailable is a stent delivery system which can be quickly and easily used in a wide variety of situations and particularly in emergency situations where a dissected arterial lining has collapsed and has occluded the flow of blood to a vital organ. The present invention satisfies this need.
In addition, because the expandable member such as a balloon is inflated, the flow of blood in the artery or vessel being treated is occluded. The balloon can only be inflated for a limited amount of time, typically on the order of 15 to 60 seconds. A longer inflation time would be desirable because it would: allow more time for the surgeon to deploy the stent; allow maximum stent to vessel conformity; and permit good artery seating of the stent. On the other hand, risks of prolonged balloon inflation time include angina or ischemic conditions in tissue distal to the catheter.
The importance of continuous blood flow during percutaneous transluminal coronary or peripheral vascular applications is recognized. Indeed, a perfusion-type dilatation catheter for angioplasty was introduced into the marketplace by Advanced Cardiovascular Systems, Inc. (ACS). This catheter, which can take the form of an over-the-wire, a fixed wire, or a rapid exchange type catheter, has one or more perfusion ports proximal and one or more perfusion ports distal to the dilatation balloon, which ports are in fluid communication with a guidewire receiving inner lumen extending to the distal end of the catheter. When the balloon is inflated to dilate a stenosis, oxygenated blood in the artery or aorta, or both, is forced through the proximal perfusion ports, through the inner lumen of the catheter, and out of the distal perfusion ports.
The rapid exchange version of the perfusion-type dilatation catheter has a short guidewire receiving sleeve or inner lumen extending through a distal portion of the catheter. The structure of the catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire. Details of such a rapid exchange type perfusion catheter are disclosed in, for example, U.S. Pat. No. 5,040,548 (Yock) and U.S. Pat. No. 5,061,273 (Yock), which are incorporated by reference herein.
Of interest is U.S. Pat. No. 5,368,566 (Crocker), which discloses a delivery and temporary stent catheter having a reinforced perfusion lumen. The temporary stent in Crocker is used only for maintaining patency of a body lumen while permitting perfusion of fluid through the lumen. Crocker is not directed to delivery of stents after angioplasty procedures.
U.S. Pat. No. 5,222,971 (Willard et al.) discloses a temporary stent for supporting a region of a vessel in a body comprising a stent portion and an actuator portion. The stent portion is comprised of an elongate perfusable vessel supporting portion, wherein the stent provides a flow path radially as well axially or longitudinally.
There is, however, still a need for a stent delivery system that includes a mechanism for perfusing blood during delivery of the stent to the deployment site.